One question -
select count(*) from table where pi...
# getting-startedh
Harish Bohara
05/05/2022, 7:05 AMOne question -
select count(*) from table where pipeline=‘TRANSACTIONAL’ and eventTime > ‘2022-05-04 221253.791’ -> this is giving count 10-20K
But if i use following to check the plan:
explain plan for select count(*) from table where pipeline=‘TRANSACTIONAL’ and eventTime > ‘2022-05-04 221253.791’
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Mark Needham
05/05/2022, 8:53 AM
@Amrish Lal any ideas?
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Harish Bohara
05/05/2022, 12:29 PMVerison 0.10.0
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Mayank
05/05/2022, 2:32 PM
I couldn’t understand the question from your message @Harish Bohara
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Mark Needham
05/05/2022, 2:33 PM
I think it's the next message with the screenshot. Like why does it say 'no matching segment'
Mark Needham
05/05/2022, 2:33 PM
when if you run the query you get a result
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Mayank
05/05/2022, 2:34 PM
Oh, thread view fooled me
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Mark Needham
05/05/2022, 2:34 PM
yeh sorry - I replied on a thread to the wrong message
Mark Needham
05/05/2022, 2:34 PM
only realised after I pressed enter
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Harish Bohara
05/05/2022, 4:21 PMYes when I run the query I get results. However if I try to check the plan it shows "no matching segments "
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Mayank
05/05/2022, 4:24 PM
I think it means number (not No)
Mayank
05/05/2022, 4:24 PM
That should be fixed
Mayank
05/05/2022, 6:29 PM
Looking at the code, seems it is really NO matching segments and not number. @Amrish Lal this seems incorrect, could you please take a look?
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Sidd
05/05/2022, 6:37 PMCan I see the output of EXPLAIN PLAN ?
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Mayank
05/05/2022, 6:38 PM
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Amrish Lal
05/05/2022, 6:42 PMI am wondering if this is caused by the fact that we pick a random segment on a random server to generate EXPLAIN PLAN output. Do they consistently get the same output if they run the EXPLAIN PLAN query multiple times?
Amrish Lal
05/05/2022, 6:44 PMRichard recently opened an issue on this which has some more details.
Amrish Lal
05/05/2022, 6:58 PM@Mayank Yes,
NO_MATCHING_SEGMENTm
Mayank
05/05/2022, 6:59 PM
@Amrish Lal Yep I saw that, I was asking why that is returned in this case, as it seems incorrect,
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Amrish Lal
05/05/2022, 7:01 PMWithout knowing more, I can only assume that they have multiple servers with multiple segments on each server and the server that we randomly picked to run EXPLAIN PLAN on did not have any matching segments. Thats why I am wondering if they see some variation in EXPLAIN PLAN output if the query is run multiple times.
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Richard Startin
05/05/2022, 8:10 PMthe problem with this approach is it bypasses pruning
Richard Startin
05/05/2022, 8:11 PMso it will claim that something pinot would never do will happen, and if you have enough segments pruned before the query evaluates you have to get really lucky to find a segment that could be used to generate a realistic plan
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